The purpose of this study is to assess the effects of a computerized drug ordering review system which reviews open drug orders against a set of established guidelines and which informs clinicians of exceptions to them. The assessment will be made in at least four institutions for the mentally retarded in which drugs are widely prescribed. Effects will be assessed in terms of clinicians' prescribing behaviors as measured by exception rates and changes in their knowledge of pharmacotherapy. Further, investigations of factors which may effect these rates such as clinician characteristics, attitudes, and other institutional and environmental factors, will be made.